Mobile data transmission and data services are constantly making progress. With the increasing usage of mobile communication, network organization and optimization is becoming more and more important. Also, in this context, according to one aspect, investigations are made to remove some communication traffic from the network and to use D2D communication between devices such as terminals. This and other aspects are being investigated, e.g. in the framework of LTE™ or LTE™-A.
Insofar, the present invention relates in particular but without limitation to mobile communications, for example to environments under WCDMA (Wideband Code Divisional Multiple Access), LTE™ (Long Term Evolution) or LTE™-A (LTE™ Advanced), UMTS (Universal Mobile Telecommunication System), 3GPP (3rd Generation Partnership Project) or any other communication scenario, potentially standardized by ETSI (European Telecommunication Standards Institute) and/or other local or regional standardization bodies e.g. NGMN (Next Generation Mobile Networks), and can advantageously be implemented as or in chipsets, or modules, or units, or apparatuses of devices (e.g. network entities such as a transceiver device also known as base station, or NodeB, or evolved NodeB eNB, or e.g. a mobility management entity MME) forming part of those networks as well as correspondingly in terminals such as user equipments UE, mobile stations MS, or the like, such as smartphones, and/or other mobile communication enabled terminals such as laptops or the like enabled to communicate via e.g. at least one (wireless) access technology such as UMTS, LTE™, WLAN, etc.
More particularly, the present invention relates to those apparatuses/units of devices or network entities and terminals that are applied in such communication networks for the purposes of discovery of devices such as terminals UE that are suitable for a D2D communication.
With the evolution of the LTE™ system, future cellular networks will become more and more complex, various and huge. For network operators, along with the usage of new technologies, how to reduce network infrastructure costs and operating expenses is a big challenge. So, under one aspect to accomplish such goal, investigations are made into D2D communication.
For example, 3GPP LTE™-A Rel-12 started to address LTE™-A support for network-controlled D2D discovery and communications. In this regard, 3GPP SA1 has already started carrying out a study for potential services and requirements for D2D discovery and communications. Those are referred to as Proximity Services (ProSe). The objective is to study use cases and to identify potential requirements for an operator network controlled discovery and communication between (D2D enabled) devices which are in proximity, under continuous network control, and which are under a 3GPP network coverage, for e.g. commercial/social use, network offloading, public safety, and/or integration of current infrastructure services, so as to assure the consistency of the user experience including reachability and mobility aspects. Additionally, the study item will study use cases and identify potential requirements for public safety, in case of absence of EUTRAN coverage (subject to regional regulation and operator policy, and limited to specific public-safety designated frequency bands and terminals).
One of fundamental requirements of ProSe is to enable a device to discover other devices in its proximity and to be discoverable. To facilitate proximity device discovery, the most often applied technique is to have the devices transmit some individual reference signals unique among a local networking neighborhood of the devices, or to broadcast some predefined beacons in certain predefined channels.
Given an increasing and huge number of terminal (UE) devices in future mobile cellular systems employing D2D discovery and communications, it becomes a big challenge to provide reliable and efficient autonomous discovery mechanism based on device broadcasted beaconing solution (i.e. each device broadcasts an individual beacon signal to enable the others to detect it) in terms of resource usage, power consumption and control overhead.
The cellular network has been developed from homogeneous network to heterogeneous network in which more and more local area nodes (e.g. micro/pico eNB's or BTS's, femto eNB's, relay nodes, WLAN (WiFi™) access points, etc.) will be deployed in certain local areas to boost capacity, extend the coverage and provide a more “environmentally friendly” radio solution.
Different aspects of device/peer discovery for D2D/P2P communication have been discussed. However, all previous proposals are based on a discovery signal (e.g. beacon/pilot signal) broadcasted by the device itself to be discovered, which broadcasted signal is used to enable the other devices to detect/discover the broadcasting device.
Allowing the device itself to broadcast a beacon/pilot signal for proximity device discovery, however, imposes a burden on spectrum usage and hence is not seen as an efficient solution from spectrum usage, power consumption and control overhead perspective, especially in the case that a large number of mobile devices with D2D/P2P communication capability are located within a certain limited local area.
Insofar as some kind of network assisted discovery was previously proposed, such “network assistance” in one case resides in that the device only performs peer discovery upon network request (instead of all the time), while in another case an enhancement was proposed in that use is made of an access point/base station to relay some discovery information sent from terminals such as mobile devices to be discovered. Hence, in such scenario, the “network assistance” resides only in a relaying of discovery signals broadcasted as usual from terminals.
Thus, there is still a need to further improve such systems.